1. Field of the Invention
The present invention relates to a device which limits a movement of a head within a hard disk drive assembly.
2. Background Information
Hard disk drives contain transducers that are magnetically coupled to one or more rotating disks. The transducers can write and read information by magnetizing the disk surface and sensing the magnetic field that flows from the disks, respectively. The transducers are integrated into a head that is mounted to a suspension. The head and suspension are typically referred to as a head gimbal assembly (HGA).
The HGA's of a hard disk drive are mounted to an actuator arm that is pivotally connected to a base plate of the drive. The drive may further include a voice coil motor that rotates the actuator arm and moves the heads across the surfaces of the disks.
Each head has an air bearing surface which cooperates with an air flow generated by the rotation of the disks to create an air bearing pressure between the transducers and the disk surfaces, while the disks are rotating. The air bearing pressure allows the head to fly over a rotating disk at a certain nominal fly height to prevent mechanical wear between the disks and the heads.
The heads are essentially suspended from the actuator arm above or below the surfaces of disks. Any shock or vibration loads essentially perpendicular to the disk surfaces may cause the heads to strike or “slap” the disks. Head slapping may damage both the heads and the disks.
Head slapping typically occurs when the shock load is great enough to cause the head to “separate” away from the disk surface. The largest head slapping forces are typically associated with the top and bottom HGAs located adjacent to the base plate and the cover plate of the disk drive, since there is a relatively large amount of space between the plates and the top and bottom HGAs. The large spaces allow the heads to move away from the disk surfaces and then slap back onto the disks.
The force required to create a head slap can be increased by reducing the length of the suspension and/or reducing the mass of the head. Reducing the length of the arm and/or the mass may create an undesirable change in the mechanical characteristic of the HGA. It would be desirable to provide a hard disk drive that limits the movement of an HGA within the drive.